Evaluation of risk of malignancy index in the preoperative assessment of ovarian tumors: Study from a tertiary care center

Objectives: Risk of malignancy index (RMI) is a mathematical formula using a combination of diagnostic modulations to predict whether an adnexal mass is benign or malignant. The aim of this study was to evaluate the diagnostic performance of RMI in differentiating benign and malignant ovarian tumors, in comparison with histopathology, the gold standard and to identify the patients with likely ovarian cancer for a referral to a specialist gynecological oncologist, for proper surgical staging and treatment. Materials and Methods: The descriptive study was done on 102 patients referred to a tertiary care center for 12 months from June 2006 to May 2007. RMI is the product of menopausal score, ultrasound score, and absolute value of serum CA-125 levels. RMI score was calculated and compared with histopathology, the gold standard. Sensitivity, specificity, positive and negative predictive values, and accuracy were calculated for individual parameters and for RMI to assess malignancy. Chi-square test, Cohen's Kappa, and receiver operator characteristic (ROC) analysis was carried out. ROC curve was drawn to conclude on the cutoff value of RMI. Results: Analyzing the diagnostic performance of RMI, we found that RMI performed better than individual parameters in differentiating benign and malignant ovarian tumors at the cutoff score of 200. The present study gives 195 as best cutoff point for RMI to differentiate benign and malignant ovarian neoplasms. Conclusion: RMI can be used by the general gynecologists at the periphery for referral of suspected ovarian tumors to oncology centers, thus improving the survival and prognosis of women undergoing surgery for ovarian tumors.